STEP file is one of modern formats for 3D model data interchange between CAD programs. STEP is an abbreviation of "STandard for the Exchange of the Product model data". STEP file format is formally defined by the International Standards Organization in the document ISO 10303. STEP files have modular structure, each module is called "class". Classes present the standard, implementation architectures, conformance testing procedures, resource information models, and application protocols. This means that the STEP is more than just a geometry data file.
But most of modern CAD programs allow exporting the 3D geometry into this format. Any of these programs may be thus used for creating geometry models for further FEA analysis with QuickField. STEP files may be imported to QuickField versions 6.1 or above.
For more information https://en.wikipedia.org/wiki/ISO_10303-21